1. Field of the Invention
The present invention relates to a pole-shaped beam supporter for use in construction works to build ferro-concrete houses or steel-frame buildings, wherein the supporter will temporarily hold in position the steel frame of an upper floor, any horizontal beam forming a temporary skeleton, a concrete mold or the like for the upper floor.
2. Prior Art
Such beam supporters have usually been set up on an already formed lower floor in order to support the upper floor skeleton or support the horizontal beam of the concrete mold for the upper floor, until subsequent removal upon finishing the latter.
The prior art beam supporters have each at an upper end thereof a single screw jack, or have each at both the upper and lower ends respective screw jacks. These jacks will be operated at their drives to extend or contract the supporters when the latter are fixed in position or removed from between the floors. Each drive is however forced to spin about the supporter""s vertical axis, as a handle protruding radially and sideways from the drive is rotated with both the hands of a worker. Operation of such beam supporters have necessitated two persons, one of them just holding the supporter upright while the other driving its screw jack or jacks, thus bringing about a noticeable inefficiency in construction works.
A primary object of the present invention made in view of this draw-back is therefore to provide a beam supporter of such a compact structure that even a single worker can hold it in place with his one hand, while operating with his other hand a drive portion of said supporter that is being extended or contracted.
A secondary object is to provide a beam supporter comprising an outer cylindrical member, a threaded rod installed therein and a gear box engaging with and driving the threaded rod, and constructed such that said rod is protected well from bending sideways between its upper end and the gear box even when the supporter extends to a maximum limit.
In order to achieve the primary object, the beam supporter provided herein will comprise an upper outer cylinder, a lower outer cylinder extending coaxially therewith, a gearbox fixedly connecting the upper cylinder to the lower cylinder, a drive bevel gear formed as a part of the gearbox and having a horizontal shaft, a driven bevel gear installed in the gearbox, engaging the drive bevel gear and having a vertical shaft, and a sleeve built in the gearbox and in parallel with the cylinders. The sleeve has an outer periphery whose intermediate portion is integral with the driven bevel gear, and the sleeve further has an inner periphery with a female thread formed thereon to extend from top to bottom of the inner periphery. The beam supporter further comprises a threaded rod in mesh with the female thread and penetrating the gearbox. The horizontal shaft of the drive bevel gear extends sideways and outwardly from the gearbox so as to provide a protrusion operable to rotate the drive bevel gear. The beam supporter still further comprises a sliding inner cylinder having a lower end secured to an upper end of the threaded rod, so that an upper end of the inner cylinder slidably protrudes a variable distance upwards from an upper opening of the upper outer cylinder when a handle or the like is used to operate the gearbox.
Preferably, the sliding inner cylinder may be inhibited from rotating relative to the upper outer cylinder. To assure that the inner cylinder does slide only in a longitudinal direction, at least one vertical groove (or more preferably, two parallel grooves) may be formed in the inner periphery of the upper outer cylinder. In such a case, a transverse pin will fix the sliding inner cylinder to the threaded rod, and this pin will have opposite ends protruding transversely and kept in a sliding engagement with the vertical grooves.
The upper end of the upper outer cylinder may have a stopper for stopping the transverse pin at its highest position, thereby protecting the sliding inner cylinder from slipping off said outer cylinder.
Freely rotatable rollers attached to the opposite ends of the pin will reduce friction so as to assist those ends to smoothly slide in and along the vertical grooves.
In order to achieve the secondary object, a ring-shaped annular plain bearing is disposed around the threaded rod and capable of vertically sliding above the gearbox. Guide sticks each of a predetermined length and depending through a cap that is secured to the upper end of the threaded rod may hold the ring-shaped bearing. The bearing is allowed to freely slide up and down, but always resting on lower stopping means that are disposed at feet of the guide sticks. Upper ends of the guide sticks comprise a stopper disposed on (and usually above) the upper face of the cap, so that those sticks are prevented from dropping off the cap.
It is preferable also in this case that the sliding inner cylinder will not rotate relative to the upper outer cylinder but merely slide therein. For this purpose, these two cylinders may respectively have longitudinal lugs and grooves engage with each other.